JPH0643278B2 - Semiconductor thin film forming method - Google Patents

Description

The present invention relates to a method for forming a single crystal semiconductor thin film on an amorphous insulating film.

[Prior Art] When forming a single crystal film, a so-called SOI film, on an insulating film, there is a method of providing an opening in a part of the insulating film and providing a so-called seed for transmitting crystal information from the single crystal substrate. S
It is effective for controlling the crystal orientation of the OI film.

[Problems to be Solved by the Invention] However, for example, an oxide film is formed as an insulating film on a single-crystal Si substrate, an opening is provided in a part thereof, and amorphous Si is adhered thereon, When heat treatment is performed at a low temperature of 600 ° C. and solid phase growth is performed in the lateral direction on the insulating film from the opening, that is, the seed portion, the distance for single crystal growth in the lateral direction from the seed is such that impurities are introduced into amorphous Si. If not, there is a problem that it is only about 10 μm (Reference, H. Ishiwara et al; Extended Abstracts of the 1
8th Conference on Solid State Devices and Material
s, Tokyo, 1986 p553).

An object of the present invention is to solve the above problems and to provide a semiconductor thin film forming method capable of forming a single crystal thin film over a large area in one direction from a seed when growing an SOI crystal. .

[Means for Solving the Problems] The present invention introduces a sample having an opening in a part of an insulating film formed on a single crystal semiconductor substrate into a gas containing semiconductor atoms for film formation, While heating the insulating film, irradiating an ion beam or an electron beam in one direction from the opening of the insulating film to attach a semiconductor film from the opening to the insulating film, and a semiconductor formed on the sample formed by the process. And a step of epitaxially growing the film.

[Function] When an amorphous film deposited on an insulating film is laterally solid-phase grown from a seed, the reason why the lateral growth distance from the seed is limited is that the entire amorphous film is solid-phase grown. This is because the polycrystal nuclei are partially grown because of being heated to the temperature, the grown polycrystal and the solid phase grown film collide with each other, and the solid phase growth is blocked there. Therefore, in order to increase the lateral growth distance from the seed, the film may be sequentially grown from the seed instead of adhering the film all over the insulating film at once and then crystallizing it. As a method, a sample heated at a low temperature is put in a gas containing film-forming atoms, and an energy beam such as an electron beam or an ion beam is irradiated from the seed portion in one direction,
There is a method of growing a film only on a portion irradiated with a beam. However, with this method, it takes time to form a film having a thickness of about 1 μm, and the surface condition deteriorates. Therefore, first, a film of about several tens of μm is formed by the above method, and then epitaxial growth is performed on the film. By doing so, it becomes possible to form an SOI film having a good surface condition and an arbitrary film thickness.

EXAMPLES Hereinafter, the present invention will be described in more detail based on examples. FIG. 1 shows a sample structure used in the present invention. In the figure, a thermal oxide film 2 of 1 μm is formed on a silicon substrate 1 of (100) orientation.
m. Next, the seed part 3 is selectively embedded with a silicon single crystal to be planarized. The sample is 35 by the substrate heating device 6.
Heat to 0 ° C. A mixed gas of silane and argon is introduced here, and then the ion beam 5 is moved from the seed 3 in one direction on the oxide film 2. As the ion beam, Si
^{+ Was} used. When the ion beam 5 is first irradiated onto the seed 3, the silane gas existing on the seed 3 is decomposed,
The seed region where silicon adheres to the seed 3 also has the effect of ions by the ion beam 5 that is simultaneously irradiated,
Silicon is epitaxially grown on the seed 3. Next, when the ion beam 5 is gradually moved from the seed 3, silicon is similarly attached only to the region irradiated with the ion beam 5. At this time, if the substrate temperature is high, the polycrystalline silicon growth rate is fast, so the polycrystalline silicon film may grow under some conditions. However, by lowering the substrate temperature, it is possible to slow the growth rate of the polycrystalline nuclei. As a result, silicon atoms are epitaxially grown on the growth layer 4 and laterally grown. In the case of the present invention, the film thickness is as thin as several tens of nm. If it takes the longest time, a thick film can be formed. However, in that case, the surface condition deteriorates and the unevenness becomes severe. So the number 10
In order to obtain a film thickness of about 0 nm, first, irradiation with an ion beam is performed to form a silicon layer having a film thickness of several 10 nm. Next, silicon was epitaxially grown on it to a predetermined film thickness, so that a silicon film that was grown in a short time and had a good surface condition could be formed. Also, the same effect was obtained by using an electron beam, and it was found that the energy beam is effective for film formation. Further, by linearizing the ion beam or the electron beam, high throughput can be realized. In fact, when using an electron beam, it is about 4-5 mm
It is possible to extract a linear electron beam with a length of about 50%, and by using such a beam, the wafer processing can be shortened by about 50 times compared with the conventional method.

[Advantages of the Invention] As described above, by using the method of the present invention, a semiconductor thin film having a large area can be formed in one direction from a seed, and an ion beam or an electron beam can be easily shaped into a linear shape. By forming a beam and using the linear beam, the wafer processing time can be significantly shortened.

[Brief description of drawings]

 FIG. 1 is a cross-sectional view of the sample used in this example. 1 ... Silicon substrate, 2 ... Oxide film 3 ... Seed, 4 ... Growth film 5 ... Ion beam, 6 ... Substrate heating device

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-60-235795 (JP, A) JP-A-61-2224 (JP, A) JP-A-59-16337 (JP, A)

Claims (1)

[Claims] 1. A sample having an opening in a part of an insulating film formed on a single crystal semiconductor substrate is introduced into a gas containing semiconductor atoms for film formation, and the insulating film is heated while heating the sample. Of irradiating an ion beam or an electron beam in one direction from the opening of the semiconductor device to attach a semiconductor film on the insulating film through the opening, and a step of epitaxially growing the semiconductor film on the sample formed by the process. A method for forming a semiconductor thin film, comprising: